Horizon, Meteors & the solar system

just watching this on BBC2 - they showed an image of the solar system & it suddenly struck me that all the planets orbit the sun on the same plane. Why is this? why don't they orbit a bit more randomly?

the theory is, when the solar system was just forming, it was a 'disc' of dust & gas that started to coalesce in the centre to form the sun and further out to form loads of rocks. many of those rocks crashed into each other & over time came to form the rocky inner planets, while the outer gas planets happened in a similar way to the sun; the more massive they got, the bigger they became, until they became the gas giants we know today.

They're all on the same plane because that's how they started out. Pluto is the odd one out but it is thought that it's a stray object from the Oort cloud where the comets live

"This is the story of the most extraordinary journey in human exploration, the Voyager space mission. In 1977 two unmanned spacecraft were launched by NASA, heading for distant worlds. It would be the first time any man-made object would ever visit the farthest planets of the solar system - Jupiter, Saturn, Neptune and Uranus. On the way the Voyagers would be bombarded by space dust, fried by radiation and discover many of the remarkable wonders of the solar system.

Now, at the end of 2012, 35 years and 11 billion miles later, they are leaving the area of the sun's influence. As they journey out into the galaxy beyond they carry a message from Earth, a golden record bolted to the side of each craft describing our civilisation in case of discovery by another. This is the definitive account of the most intrepid explorers in Earth's history. (R)"